Balancing machine



Sept. 6, .1932. H. M. STEPHENSON BALANCING MACHINE Filed 001;. 22, 1929 Inventor: Hu h M. Stephenson (4 860. His Attorney- U Patented Sept. 6, 1932 UNITED STATES PATENT OFFICE HUGH M. STEPHENSON, OE FORT WAYNE, INDIANA, ASSIGNOR TO GENERAL ELECTRIC} COMPANY, A CORPORATION OF NEW YORK BALANCING MACHINE Application filed October 22, 1929. Serial No. 401,590.

The present invention relates to balancing machine for use in determining the unbalance in rotating bodies, either static unbalance, dynamic unbalance, or both, and the location and amount of weight required to be added or substracted in order to place the body in balance, and has for its object to provide an improved machine ofthis type.

For a consideration of what I believe to be novel and my invention, attention is directed to the following description and the claims appended thereto.

In the drawing, Fig. 1- is a perspective view of a machine embodying my invention.-

In this view, certain parts which in actual practice would be made strong and rigid, and firmly connected together, are shown diagrammatically as being relatively small in cross section and as being spaced one from another and connected together by elongated means, the purpose being to make the drawing easier to understand. Fig. 2 is an end view of certain parts of the machine. Figs. 3, 4 and 5 are detail sectional views of cross bars Which form parts of the machine.

Referringto the drawing, 1 indicates a bed plate which may be mounted on a suitable supportor foundation, and which carries the movingparts of the balancing machine. Mounted on bed plate 1 is a frame pivoted at a central point so that it is free to'oscillate or vibrate in a plane parallel to the plane of the bed plate. The frame comprises two side bars 2 and 3 connected together at one end by a cross rod 4 and at the other end by a bearing yoke 5, and connected together at an intermediate point by a cross barb. Cross barb is rigidly connected to side bar 2 and is connected to. side bar 3 by a thumb-screw 7, the end of cross bar, 6 being provided with a recess in which side bar 3 is located, as shown more particularly in Fig. 3. Cross bar 6 is provided with a downwardly projecting foot 8 which rests on the bed plate 1 and is connected to it by a pivot pin 9. Thisforms a central pivotal support for the vibratory frame, which permits the frame to vibrate or oscillate in a plane parallel to the bed plate. The; frame is'supported also at suitable points by a num'- ber of slender flexible rods 10, which are rigidly fixed to the frame and have pointed ends which rest in cone-shaped recesses 11 in the bed plate. Surrounding each rod 10 is a sleeve 12 which serves to limit the flexing of the rods. In the present instance, three rods are illustrated (see Fig. 1). However, a greater or lesser number may be utilized as required or found desirable in" any particular instance.

Side bars 2 and 3, on their inwardly facing sides are tapered in section to form guideways on which slide two bearings indicated as a whole by reference numerals 13 and 14, the bearings being supported by the side bars. These bearings are shown in the drawingin a diagrammatic manner, the several parts being shown spaced apart and as being relatively small, in order that the general features of their construction can be readily seen. It will be understood, however, that in actual practice each bearing will be formed of closely associated relatively heavy rigid parts to meet the known requirements of balancing machines- Each bearing comprises a cross bar 15 having notched ends which engage bars 2 and 3 and are adapted to slide along such 1 bars. (See Fig. 4) When thumbscrew 7 is tightened against bar 3, bar 3 is flexed in wardly somewhat, thus clamping cross bars 15 tightly between bars 2 and 3. When thumbscrew 7 is loosened, side bar 3 will spring outward slightly, whereby cross bars 15are released sufliciently to admit of their being slid along side bars 2 and3 which serve as ways. Projecting upwardly on cross bar 15 is a standard 16, which forms a' support for two bearing arms 17 and 18. Pivotally mounted in bearing arms 17 and 18 are shafts 19 and 20. At one end shafts 19 and 20 car rollers 21 which form a support and driving,

means for the shaft of the body to be balanced,

' and at their other ends they carry pulleys 21a for a driving belt 2172. Bearing arms 17 and 18 are arranged so they can be adjusted to ad- ]ust rollers 21 toward and away; from each other, so as to adapt the rollers 21 for receivas being clamped against shoulders 23 on standard 16 by means of a rod 24 which extends through the shoulders and has a collar 24a which clamps against arm 17 and a thumb-screw 25 which clamps against arm 18. Also the two arms are shown as being connected together through the intermediary of nuts 26 on a right and left hand threaded rod 27, having at its central portion a disc 28 by means of which it may be turned. By releasing thumb-screw 25 and turning disc 28 to turn rod 27, nuts 26 may be moved along rod 27 to effect movement of arms 17 and 18 toward or away from each other and then clamped in the desired adjusted'position by again tightening the thumb-screw 25. The arrangement illustrated for accomplishing this result is only diagrammatic, and it will be understood that any suitable mechanical construction may be utilized. Also, it will be understood that in certain instances, for example, where the machine is intended for balancing always the same size of body, it may be unnecessary to provide an adjusting means for the rollers 21, as the bearings may be built in the first instance with the rollers spaced the required distance apart for the work to be performed by the machine. Under these circumstances, the arms 17 and 18 may be formed as an integral part of standard 16.

Extending longitudinally of the frame midway between side bars 2 and 3 is a jack shaft 29, which is pivotally mounted in cross bars 6 and 15. At cross bar 6 it carries a driving pulley 30 connected by a belt 31 to a suitable driving motor 32. Adjacent to each bearing 13 and 14, the jack shaft is provided with a pulley 33 over which passes the belt 21?), an intermediate pulley 34 being provided for the belt on the end of rod 24. This belt arrangement permits of the arms 17 and 18 being adjusted relatively to each other without the necessity of loosening or tightening the belt. Pulley 33 in each instance forms a part of the bearing'13 or the bearing 14, and it is shown connected to it diagrammatically-by means of a-rod 35 fixed to arm 17 and having a forked end in which the pulley is located. When motor 32 is running. it will be seen that it drives jack shaft 29, which in turn drives the bearing rollers 21 through the belt 215.

The cross bar 15, standard 16, arms 17 and 18, shafts 19 and 20 carried by arms 17 and 18, rollers 21, pulleys 21a and a pulley 33 form a unitary structure which is in the one instance designated by the numeral 13 and in the other instance by the numeral 14. As before stated," the parts of each bearing are shown more or less diagrammatically and as spaced apart. In actual practice, as will be understood, arms 17 and 18 will be preferably directly adjacent to standardlti; shafts 19 and 20 will be relatively short and substantial with rollers 21 and pulleys 21a directly adjacent to the bearings for the shafts, and the connecting parts will be such as to provide a rigid bearing construction. Each bearing structure is movable along ways 2 and 3 as a unit. The two bearings 13 and 14 are connected to each other in spaced relation by a rod 36, which is fixed to cross bar 15 of bearing 14, and is fastened to cross-bar 15 of bearing 13 by a thumb-screw 37. By loosening thumb-screw 37, bearings 13 and 14 may be adjusted toward or away-from each other, so as to space the two sets of rollers 21 the correct distance apart to receive the body to be balanced. The thumb screw 37 can then be tightened to fix the two bearings 13 and 14 relatively to each other.

In carrying out the balancing operation, it is necessary, in order to correct for dynamic unbalance, to have two planes of correction.

One plane of correction is located over the pivot pin 9, while the weight to be added or removed in the other plane of correction is being determined, after which the second plane of correction is placed over the pivot pin 9 while the weight to be added or removed in the first plane of correction is being determined. This result may be accomplished by reversing the position of the body to be balanced in its bearings. However, in actual practice it is more convenient to move the body to be balanced longitudinally of the balancing machine than to reverse the position of the body. This can be accomplished with the present machine by moving the two bearings 13 and 14 along the ways 2 and 3. To make this convenient, there is provided a guide rod 38 which is anchored in cross bar 6 and extends loosely through openings in cross bars 15. On guide rod 38 are'adjustablc stops 39 (only one of which is shown in the drawing), these stops being spaced apart a distance equal to the distance between the two planes of correction. By this means, when the body is being balanced, the bearings can be set first in the position wherein the one plane. of correction is over the bearing support 9, and then in the position wherein the other plane of correction is over the bearing support 9, by simply moving the bearings from engagement with one stop into engagement with the other stop.

Mounted in bearing yoke 5 is a shaft 40 which at its left-hand end is provided with a chuck 41 by means of which shaft 40 is connected to the shaft of the body to be balanced, whereby shaft 40 will be rotating with the body. Splined on shaft 40 is a cylinder 42 formed of non-magnetic material. Cylina der 42 is held from movement in a longitudinal direction by a guide 42 projecting from bearing yoke 5'. :Shaft 40 extends well beyond cylinder 42 and slides through it when bear-- ings 13 and 14 are moved longitudinally of the frame. The spline forms a driving conone on each side of cylinder 42. Poles 46 are relatively thin and wide, and are twisted at an angle such that their ends correspond with the pitch of the spiral strip 43. The ends of the poles are spaced slightly away from the spiral strip so that cylinder 42 may have a limited transverse movement between the .poles.

Since the two pole pieces 46 are directly opposite each other, while the strip 43 extends spirally of cylinder 42, it will be seen that the strip can be in line with the face of only one pole piece at a time. For example, in Fig. 1 the face of the pole piece which shows in the drawing is in line with the strip 43, and it' will be clear that the face of the pole piece on the opposite side of cylinder 42 will now be spaced from strip 43 a distance equal to one-half the pitch of the spiral. If now cylinder 42 is turned to an angle of 180 the spiral strip will first move away from the face of the pole piece shown in Fig. 1 and then at the end of the 180 movement it will be brought into line with the face of the pole piece on the opposite side of the cylinder.

With this arrangement it will be seen that when the cylinder is rotating the spiral strip 43 is alternately brought into line with the face of first one pole piece and then the other pole piece.

Yoke 45 is provided with a dove-tailed groove 47 in its lower surface whichslides on a key 48 fixed to base plate 1, whereby the yoke may be moved relatively to base 1.

This permits e-lectro-magnet 44 and pole pieces 46 to be adjusted longitudinally relatively to cylinder 42. The adjustment may be effected by means of a pinion 49 which engages a rack50 on the under side of yoke 45, and is adapted to be turned by a thumbpiece 51.

Connected to electro-magnet 44 by lead wires 52 is a source of electrical energy 53,

an ammeter 54, and an adjustable resistance its axially movable shaft located against the end of the one side bar 3. This instrument serves to indicate the amplitude of vibration of the frame in the horizontal plane. tion indicators of this type are well known,

Vibraand accordingly the instrument is indicated only diagrammatically.

The operation is as follows:

The bearing rollers 21 of the two bearings 13 and 14 having been set the desired distance apart, the body to be balanced, which is indicated by dotted lines at 57, is placed on the rollers 21 and connected to shaft 40 by the chuck 41. Thumb-screw 7 is released and the two bearings are moved as a unit into.

engagement with the one stop 39 soas to brlng the first plane of correction over the pivot pin 9. The thumb-screw 7 is then.

tightened to clamp the hearings in this position. In the drawing, the plane of correction at the left-hand end of the body to be balanced is shown as being located over the pivot pin. Motor 32 is now operated to rotate the body 57 at a suitable speed and rheostat is set to energize electromagnet 44 by a suitable amount. If the body is unbalanced either statically or dynamically, it

will tend to effect vibration of the frame about pivot pin 9 in a horizontal plane, the amplitude of the vibrations being read on the vibration indicating instrument 56. Cylinder 42 rotates along with the body 57, and as it rotates it brings the spirally wound strip 43 into. line, first with the one pole piece 46 and then with the other pole piece 46. Electromagnet 44 being energized, as the spiral strip passes in front of first one pole piece and then the other, there is given to the frame a pull in the horizontal plane, first in one direction and then in the other direction, tending to vibrate the frame.

Since the pole pieces are directly opposite each other it will be seen that the two impulses imparted to the cylinder 42 and hence to the vibratory frame on each revolution of the cylinder are 180 apart, and both are imparted in the same certain plane through the body 57, it being the plane through the body which is horizontal at the time either pole piece is in line with strip 43. The plane through body 57 which is horizontal at the time of the impulses from the pole pieces can be varied by moving the pole pieces longitudinally relatively to cylinder 42, so that by mov-.

ing the pole pieces, a position for them can be reached in which the impulses imparted to the frame by the ole pieces lie in the same plane through bod y 57 and are in a direction opposite to that of the impulses imparted to the frame due to the unbalance of the body 57. Accordingly, by adjusting pole pieces 46 relatively to cylinder 42, a position of minimum vibration of the frame is obtained. Then the result will have been accomplished, that the impulses imparted to the frame by the pole pieces are in the same plane through body 57 as are the impulses imparted to the frame I due to the unbalance in the body 57 but are 180 displaced therefrom. Now, by adjust ing resistance 55, the strength of the pull of lot the electromagnet can be varied until the impulses imparted to the frame by the pole pieces exactly equal and are opposite to the mpulses imparted to the frame by the rotating body so that the frame will cease to vibrate. Now, by stopping the machine and rotating the body until the strip 43 is directly 1n line with the face of one of the pole pieces 46, the plane of the unbalance is found, it belng a horizontal plane through the center of the body, and by reading the ammeter 54, the amount of the unbalance can be determined, the amount of the unbalance being a function of the amount of electrical energy required'by the electro-magnet to overcome 1t. There is thus obtained the location and the amount of correction for the one plane of correction.

The operator now unscrews thumb-screw 7 and moves the bearings with the piece to be balanced therein, along the guides 2 and 3 1nto engagement with the other stop 39, whereby the right-hand plane of correction is brought over the pivot pin 9. The operation just described is then repeated for the second plane of correction, whereby there is obtained an indication of the plane of correctlon andthe amount of correction required, as before explained. Following this, the body maybe balanced by adding or removin the requlred amounts of weight in the two p anes of correction, as is well understood. The ammeter may be calibrated in connection with the machine and tables or curves prepared from which the required weights may be read.

In balancing continuously bodies of the same character, a table or curve may be prepared showing the current required to neutralize vibrations of the frame for varying amounts of imbalance of the body. The operator may then in balancing a body first note on the vibration indicators 56 the total' .amount of unbalance, the electro-magnet 44 being unenergized, and by reference to the table or curve immediatelyset the rheostat 55 for the required amount of current. Then it remains only to determine the plane of the unbalance, which may be done by moving the pole pieces 46 to the position of zero vibration.

By my invention, it will be seen that I am enabled to determine quickly and accurately the amount of unbalance in a body and the plane in which weight must be added or subtracted to balance the body.

Also, by my invention, I am enabled to make a preliminary check to"deter1nine the nature of the unbalance of the body, that is, whether it is wholly static unbalance, wholly dynamic unbalance or a combination of the two. If after the body has been placed on the bearing rollers and run up to speed, but before the circuit on electro-magnet 44 is closed, the thumb-screw 7 is loosened slightly and the bearings carrying therevolving body 57 are slid along the ways as a unit from one extreme position to the other, and the indicator 56 during this movement shows zero vibration in one point, that is, passes through zero amplitude, the body is only out of static balance and can be corrected by adding or subtracting weight in a single plane, the amount and location of the weight being determined for one plane after the manner already described.

If when the bearings and the body supported thereon are moved from one extreme position to the other, there is no change in the amplitude of vibration as shown by the indicator, the body is out of balance dynamically onlyand can be corrected by determining the correction for one balance plane and then correcting a like amount in the other balance plane on the opposite side from the first correction. l

If the body and its supports are moved from one extreme position to the other and the vibration indicator changes in its amplitude but does not pass through zero vibration, the body is affected by a general unbalance consisting of both static and dynamic unbalance, and will require balancing in two planes of correction.

In accordance with the provision of the patent statute, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a balancing machine, the combination of a base, a frame pivotally mounted on the base and free to vibrate in one plane, means carried by the frame for supporting a body to be balanced, means for rotating a body on said supporting means, said supporting means being slidable as a unit along said frame whereby either end of said body may be positioned above said pivot, means for locking said supporting means to said frame, means for applying vibratory impulses to the frame in sa d plane, and means for varying the strength of said impulses and the plane through the rotating body in which the impulses are applied.

2. In a balancing machine, the combination' of a base, a frame pivotally mounted on the base and free to vibrate in one plane,

means carried by the frame for supportinga body to be balanced, means for rotating a body on said support ng means, said supporting means being slidable as a unit along said frame whereby either end of said body may bepositioned above said pivot, means for locking said supporting means to said frame, means for applying vibratory impulses to the frame in said plane, and means for varying the plane through the rotating body in which said impulses are applied.

3. In a balancing machine, the combination of a base, a frame pivotally mounted on the base and free to vibrate in one plane, means carried by the frame for supporting a body to be balanced, means for rotating a body on said supporting means, said supporting means being slidable as a unit along said frame whereby either end of said body may be positioned above said pivot, means for locking said supporting means to said frame, electromagnetic means for applying vibratory impulses to the frame in said plane, and means for varying the plane through the rotating body in which said impulses are applied.

4. In a balancing machine, the combination of abase, a frame pivotally mounted on the base and free to vibrate in one plane, means carried by the frame for supporting a body to be balanced, means for rotating a body on said supporting means, said supporting means being slidable as a unit along said frame whereby either end of said body may be positioned above said pivot, means for locking said supporting means to said frame,

' electromagnetic means for appl ing vibratory im ulses to the frame in sar plane, and means or varying the plane through the rotating body in which said impulses are'applied and the strength of said impulses.

5. In a balancing machine, the combination of a base, a frame pivotally mounted on the base and free to vibrate in one plane, means carried by the frame for supporting a body to be balanced, means for rotating a body on saidsupporting means, said supporting means being slidable as a unit along said frame whereby either end of said body may be positioned above. said pivot, means for locking said supporting means to said frame, electromagnetic means for applying vibratory. impulses to said frame in synchronism with the rate of rotation of the body being balanced, and means for varying the plane through the rotating body in which said impulses are applied 6. In a balancing machine, the combination of a base, a frame mounted on the base and free to vibrate in one plane, means carried by the frame for supporting a body to be balanced, means for rotating a body on said supporting means, means for applying vibratory impulses to said frame and for varying the plane throughthe rotating body in which said impulses are applied, said last named means comprising a magnetic member which rotates with the body, an adjacent non-rotating magnetic member, and means for adj usting said members relatively to each other.

7. In a balancing machine, the combination of a base, a-frame mounted on the base and free to vibrate in one plane, means carried by theframe for supporting a body to be balance, means for rotating a body on said supporting means, means for applying vibratory impulses to'saidframe and for varying the plane through the rotating body in which said impulses are applied, said last named means comprising a spirally extending magnet-1c member which rotates with the body, an ad acent non-rotating magnetic member, and

means for adjusting said members relativelv f 5 to each other.

8. In a. balancing machine, the combination of a base, a frame mountedon the base'and free to vibrate in one plane, means carried by the frame for supporting a body to be balanced, means for rotating a body on said supporting means, a cylinder whichrotates with the body to be balanced, a spirally extending magnetic member carried by said cylinder, a magnetic member adjacent to. said cylinder, and means for adjusting said magnetic members relatively to each other.

9. In a balancing machine, the combination of a base, a frame mounted on the base and free to vibrate in one plane, means carried by the framefor supporting a body to be balanced, means for rotating a body on said supporting means, a cylinder which rotates with the body to be balanced, a spirally extending magnetic member carried by said cylinder, an electromagnet the poles of which are adjacent to said magnetic member, means for adjusting said member and poles relatively to each other, and means for varying the strength of said electromagnet.

10. In a balancing machine, the combination of a base, a frame mounted on the base and free to vibrate in one plane about a pivot point, bearings carried by the frame, each bearing comprising a pair of rollers adapted to support a shaft, means for adjusting the rollers of each pair relatively to each other, means for fastening said bearings to ether a fixed distance apart, and means for a justing said bearings as a unit relatively to said pivot point.

11. In a balancing machine, a base, a frame pivotally mounted on the base and free to vibrate' in a plane parallel to the base, said frame having longtudinally extending guide ways, bearings supported on said guide ways and adjustable along them to bring either bearing into proximity to the pivot point of the frame, and means whereby said bearings may be simultaneously adjusted along the guide ways and locked thereto in adjusted position,

balancing machine, a base, a frame pivotally mounted on the base and free to together a fixed distance apart, and means for locking the hearings to the guide ways.

13. In a balancing machine, a frame pivoted at one point and free to vibrate in one fi'plane about said point, said pivot being located in a plane of correction, means located on opposite sides of the pivot and in spaced relation thereto forming additional supports for the frame to restrict its vibratory movements to said plane, bearings carried by the frame and adjustable relative thereto for supporting a body to be balanced means for rtating said body, means for loclzing said bearings to said frame, means for applying to said frame vibratory impulses of a frequency corresponding'to the rate of rotation of the body being balanced, and means for adjusting the time of application of said impulses whereby the plane through the body to be balanced which is parallel to the plane of vibration at the time the impulses occur may be varied.

14. In a balancing machine, a frame pivoted at one point and free to vibrate in one plane about said point, said pivot being located in a plane of correction, means located on opposite sides of the pivot and in spaced relation thereto forming additional supports for the frame to restrict its vibratory movements to said plane, bearings carried by the frame and adjustable, relative thereto for supporting a body to be balanced, means for rotating said body, means for locking said bearings to said frame, means for applying to said frame vibratory impulses of a frequency corresponding to the rate of rotation of the body being balanced, means for adjusting the time of application of said impulses whereby the plane through the body to be balanced which is parallel to the plane of vibration at the time the impulses occur may be varied, and means for varying. the,

strength of the vibratory impulses.

15;In a balancing machine, a frame pivoted at one point and free to vibrate in one plane about said point, bearings carried by the frame and adjustable relative thereto for supporting a body to be balanced, means for rotating said b0 y, means for locking said bearings to 'said frame, electromagnetic means for applying to said frame vibratory impulses of a frequency corresponding to the rate of rotation of the body being balanced, and means for adjusting the time of application of said impulses whereby the plane through the body to be balanced which is parallel to the plane of vibration at the time the impulses occur may be varied.

16. In a balancing machine, the combination of a base, a frame mounted on the base 60 and free to vibrate in one plane about a pivot point, bearings carried by the frame, said bearings comprising rollers adapted to sup port a shaft, means for fastening saidbearings together a fixed distance apart, means for adjusting said bearings as a unit relativeemma ly to said pivot point, and means for driving said rollers in any adjusted position of the bearin In wltness whereof, I have hereunto set my hand this 18th day of October, 1929.

HUGH M. STEPHENSON. 

